Men who had a daughter at age 50 or older were 79
percent more likely to have a grandchild with autism compared to men who
fathered when they were in their early 20s, the research team reported in the
March 20 issue of the journal JAMA Psychiatry. Men who fathered a son at age 50
or older had a 67 percent higher risk of having a grandchild with the disorder
compared to men who fathered a child as young adults.

"We tend to think in terms of the here and now
when we talk about the effect of the environment on our genome," said
study co-author Dr. Avi Reichenberg, who worked on the study while at King's
College London's Institute of Psychiatry, in England. "For the first time
in psychiatry, we show that your father's and grandfather's lifestyle choices
can affect you.

"This doesn't mean that you shouldn't have
children if your father was old when he had you, because while the risk is
increased, it is still small," added Reichenberg, who is now an autism
researcher at the Icahn School of Medicine at Mount Sinai, in New York City.
"However, the findings are important in understanding the complex way in
which autism develops."

Although the study found a correlation between
advanced age in grandfathers and the odds for autism in children, it is only an
observational trial, so it cannot prove cause and effect. And another expert
also stressed that the absolute risk to any one family remains small.

"Although there was a statistically
significant increase in the incidence of autism in families with older
grandparents, it must be remembered that autism was still extremely infrequent
even in families with the oldest grandparents," said Dr. Andrew Adesman,
chief of developmental and behavioral pediatrics at Steven & Alexandra
Cohen Children's Medical Center of New York, in New Hyde Park. "Thus,
older parents and grandparents should not be unduly worried."

The new research was published on the same day that
the U.S. Centers for Disease Control and Prevention announced that one in every
50 U.S. school children now has an autism spectrum disorder — up from the 2007
estimate of 1 in 88. The CDC says improved detection and diagnosis are probably
responsible for most of that increase.

In the new study, researchers looked at data from
Sweden's national registries and compared about 6,000 people with autism to
about 31,000 people without the condition. They looked at the age of each
person's maternal and paternal grandfather at the time of the individual's
birth.

The link between autism and a grandfather's age was
significant, the team said, and pointed to the genetic underpinnings of the
condition. They noted that previous studies have found a link between older
fathers and rising odds for autism in their children, such that men who have a
child when age 50 or older have a double the risk of having a child with the disorder.

Mutations lying within sperm cells might be the
culprit, the researchers said. Sperm cells undergo division throughout the
lifespan, and with each new division errors in the genome can occur. Some of
these mutations might remain "silent" in a man's child but then
accumulate or re-emerge to cause problems in future generations.

"These findings add further support to the
belief that subtle genetic abnormalities — defects that were previously
undetectable — are likely responsible for some cases of autism," Adesman
said.

This type of research might lead to tests that
could pinpoint a child's odds for an autism spectrum disorder, he added.
"Newer molecular genetic laboratory tests will increasingly allow
scientists and doctors to find atypical parts of chromosomes that put a child
at increased risk for an autism spectrum disorder," Adesman said.

Another expert said the new study could raise as
many questions as it answers.

Although the researchers offer theories as to how a
man's age might affect the risk for autism in his descendants, "more
research is needed to better understand how this occurs," said Alycia
Halladay, senior director for environmental and clinical sciences at the
advocacy group Autism Speaks. "For example, it could be through
modifications of DNA, or it could result from environmental factors modifying how
DNA is expressed," she said.

"This study is important because it utilizes
rich datasets with health record information," Halladay added. "This
approach can open the door for future work on genetic and environmental factors
associated with [autism spectrum disorders]."

This site complies with the HONcode standard for trustworthy health information: verify here.

Advertising Notice

This Site and third parties who place advertisements on this Site may collect and use information about
your visits to this Site and other websites in order to provide advertisements about goods and services of
interest to you. If you would like to obtain more information about these advertising practices and to make
choices about online behavioral advertising, please click here.